GDIVA is a tool to easily upload files to a DIVA mp3 player or similar.
The problem I found using "cp" in command line is that you don't know the time it's gonna take, and with Nautilus you can't copy the files in the order you want.
So this program lets you easily compose a list of files to copy, even files taken from a playlist, reorder the list by drag'n'drop, until it reaches the limit of the device capacity, and then, by pressing start, copying all the files, showing complete information of remaining time, and progress bars.

* The assumption of GLib and GTK+ by default is that filenames on the
filesystem are encoded in UTF-8 rather than the encoding of the locale;
The GTK+ developers consider that having filenames whose interpretation
depends on the current locale is fundamentally a bad idea.
If you have filenames encoded in the encoding of your locale, then
you may want to set the G_BROKEN_FILENAMES environment variable:
G_BROKEN_FILENAMES=1
export G_BROKEN_FILENAMES
Best integration of GTK+-2.0 with the environment is achieved by
using a UTF-8 locale.

Else, a bug with the disk usage feedback was fixed

25 sep 2002 - 0.4 released. Now you can drag'n'drop from nautilus to add files (dragging to "add files" button or to the list of songs) or songs from a playlist, dragging the list to the "add from list" button.
Else, there's a little better error feedback, and some bugs are fixed. And the "Exec when finished" should work now.